In the prior art, such a flap is generally displaced by mechanical control means (a knob or a lever) disposed on the vehicle dashboard and connected to the flap by mechanical motion transmission means including levers and cable(s). This often results in the flap being stiff to maneuver.
Proposals have thus already been made to move such a flap by means of a single-action actuator whose piston rod is connected to the flap to be moved and also to a fluid distributor valve which is actuated by the control means provided on the vehicle dashboard and which is connected firstly to the actuator feed orifice and secondly to a source of fluid under pressure and to an exhaust. In a motor vehicle, the source of fluid under pressure is generally air at reduced pressure, i.e. at a pressure that is less than atmospheric, with the low pressure air being taken from the inlet manifold of the internal combustion engine of the vehicle, and the exhaust being constituted by a simple connection to the atmosphere. As a result, the flap generally becomes much easier to maneuver, since it requires the user to apply a substantially constant force to the control means, and the flap generally returns automatically to a privileged safety position in the event of a fault or an interruption in the source of fluid under pressure.
Generally speaking, the fluid distributor valve used comprises a first moving element which is moved by the control means provided on the dashboard, and a second moving element which is connected by motion transmission means to the flap to be displaced, with said two moving elements of the distributor valve defining fluid chambers therebetween which are selectively connected firstly to the source of fluid under pressure or the exhaust by means of ducts in the first moving element, and secondly to the actuator feed orifice by means of a duct in the second moving element.
In order to reduce the maneuvering force which a user must apply to the control means, proposals have already been made to mount the fluid distributor valve on the dashboard so that its first moving element may be fixed directly to the control means and can thus be directly driven by the user. The actuator is generally in the vicinity of the flap to be displaced with its piston rod being directly connected to said flap or to a shaft on which the flap is mounted. In this case, the length of the fluid connection between the distributor valve and the actuator is generally rather long, and the means for transmitting motion from the flap to the second moving element of the distributor valve also become rather long so that the connection loop between the fluid valve, the actuator, and the flap is long, thereby reducing the speed and accuracy of control.
One of the aims of the present invention is to mitigate this drawback.
Another aim of the invention is to provide a device for controlling the displacement of a moving member, such as a flap, which device is particularly compact and capable of being standardized with the standardized device being adapted to a given flap by adapting solely the mans for transmitting motion between said device and the flap.
Another aim of the invention is to provide such a control device which also has the advantage of having fixed fluid connections to the source of fluid under pressure and to the actuator.